Are UI Color Ramps Possible through Python
While I don't think you can add a new property to an object that can hold the colour ramp data you can display a duplicate of an existing colour ramp in your own panel if you want to. As you want to display the colour ramp that exists within the nodes of an existing material, this can be done with -

cr_node = bpy.data.materials['Material'].node_tree.nodes['ColorRamp']
layout.template_color_ramp(cr_node, "color_ramp", expand=True)


As the name of the colour ramp node may change you will need a way to choose which colour ramp to display, or show all colour ramps in the current material.